Electrical contactor



2 Sheets-Sheet 1 ELECTRICAL CONTACTOR G. C. ARMSTRONG ET AL OriginalFiled Aug. 28, 1956 May 7, 1940.

WITNESSES:

.MM ff' May 7, 1940 G. c. ARMSTRONG ET Al. 2.200,070

ELECTRICAL CONTACTO R original Filed Aug. 28, 19:56 2 sheets-sheet 2[n50/@#00 C Q G INVENTORS George C? Aff/m fr0/7g Patented May 7, 1940PATENT OFFICE ELEC'rItIoAL coN'rAC'roR George C. Armstrong, Wilkinsburg,and Delbert Ellis, Forest Hills, Pa., assignors to Westinghouse Electric& Manufacturing Company, East Pittsburgh, Pa., a corporation o!Pennsylvania Original application August 28, 1936, Serial No. 98,322,now Patent No. 2,157,843, dated May 9, 1939. Divided and thisapplication August 6,

1937, Serial No. 157,652

10 claims. (cl. 20o-147) Y' l,

Our invention relates to magnetically-actuated switches or contactors,and it has particular'relation toimprovements in the design and construction of contactors adapted for use in alter-n nating-currentcircuits. A

This application is a division of our copending application, Serial No.98,322 for Electrical contactors, flledAugust 28, 1936, now Patent No.2,157,843, dated May 9, 1939, and assigned to the same assignee as thisapplication.

An object of our invention is to provide a selfcontainedunit-constructed contactor which in multi-pole designs of high currentrating may be completely assembled, adjusted and tested before beingmounted upon a porting structure. I

Another object is to provide a mechanically rugged and compactconstruction wherein all parts of replaceable or adjustable characterare accessible from the front of the mounting panel.

A further vobject is to provide a contactor of Y the iype above.described which is tilt and shock proc A still further obect is toimprove the design and arrangement of the movable-contact parts whichare employed in the above and other contactors.

Our invention, together with additional objects and advantages, willbest be understood through the following description of a specificembodiment when taken in conjunction with the accompanying drawings inwhich:

Figure 1 is a perspective view of a contactor which incorporates theseveral improvements of our invention,

Fig. 2' is a view in side elevation of the device oi' Fig. 1 showing itsadaptability for mounting upon and complete access from the front of asupporting panel,

Fig. 3 is a view in rear elevation of the device of Fig. 1, and A Figs.4, 5 and 6 are views showing our improved design oi' moving contactassemblage.

The contactor which wehave represented in the drawings as incorporatingthe several features of our invention is a three-pole device of theshaftdriven vertical-lift-type. As best shown-by Figs. 1, 2 and 3. itcomprises stationary contact members I0, cooperating movable members I2,an engagement-determining magnet I4-3ll'32 and a frame I 6 in the formof a U-shaped bar ci metal adapted to be mounted in the invertedposition illustrated. 'I'he circuit to be controlled (not shown) -isconnected with the stationary panel or other sup- 'A contacts throughlugs 2B and with the moving contacts through iiexible shunts 22.

Associated with each set of contacts Ill-I2 is an arc box 23 supportedby a blow-out coil 25. 'I'hese boxes form a part of an improvedarcquenching equipment more completely shown and described by ourcopending application for Elec-1 trical contactors, Serial No. 98,324,filed August 28, 1936,. now Patent No. 2,147,430, dated February 14,1939. In order better to show the construction and arrangement of thedevice contact parts, the view of Fig. 1 illustrates only one of thethree boxes 23 in position and shows onlyone of the three moving contactmembers I2 in place. The U-shaped frame I6 is adapted to position thedevice contacts and magnet in full operative relation and to support thecomplete contactor from a mounting panel or other supporting structureI8 (Fig. 2). It supports the stationary contacts III from its upperportion by means of a slab 24 of insulating material. It supports themovable contacts I2 pivotally between the lower p gust 28, 1936, nowPatent 2,157,844, dated May As long as the magnet winding I4 isdeenergized. gravity holds the armature in the lowermost positionillustrated in which the movable contacts I2 are separated from thestationary members I0. Energization of the winding I4 from any suitablecircuit (also not shown) attracts the armature upwardly to rotate thebar 26 into the contact-engaging position, thereby completing thecontrolled circuit.

Springs 33 form a part of the connections between bar 26 and movablecontacts I2. When energized the magnet rotates the bar somewhat beyondthe point of initial contact engagement. This motion compresses thesprings, providing the pressure of electrical contact and storing energywhich, during the opening of the device increases, the speed ofseparation of the contacts.

I'he deenergization of the magnet winding releases the armature 30. Byaction of gravity and the force of springs 33, the armature is urged lthe device from the mounting panel may be downwardly, causing thecontacts I2 to separate from the contact members I with a rapidity andthrough a distance sufficient to interrupt the controlled-circuitcurrent.

The form of construction just described offers a number of advantages.The support by frame I6 of all essential parts of the contacter in fulloperative relation permits the device to be completely assembled,adjusted and tested before being mounted on a panel. The single-pieceframe I6 shown may, of course, be replaced by a multipiece form ofconstruction. In either case this frame constitutes the backbone of thecomplete unit-assembled contactor. It is rigid, has no loose joints, andis not subject to distortion. The ends may, by a single operation duringmanufacture, be drilled and line-reamed to constitute the bearings whichaccommodate shaft-bar pins 28.

The attachment of the contactor to the panel is readily effected. Onepreferred manner ernploys tapped spacers, shown at 34 in Fig. 2, andcooperating bolts 36 and 36. The three bolts 36, which are inserted'fromthe front of the panel, pass through holes 40 (Fig. 3) in the frame I6.

Instead of using the spacers 34 at the magnety end of the contactor,separation 'of that end of eiifected by a bracket 31 (Figs. 2 and 3). Inthat case the members. 34 need serve only to interconnect bolts 36 and36.

Our improved contactor is also adapted for mounting on a steel or othermetal panel. The only changes required in the form of attachmentillustrated are the provision of insulating bushings (not shown) for thecircuit-connecting studs or terminals.

In our improved design all parts of replaceable or adjustable characterare completely accessible from the front of the mounting panel. With theform of mounting shown in Fig. 2, the complete device may be removed andreplaced by a duplicate unit without disturbing the rear of the panel.This minimizes the danger and inconvenience incident to workon thecontactor, it being necessary to deenergize only the circuits of directconnection.

'Ihe use of moving parts adapted for vertical lift results in a devicewhich is substantially shock and tilt proof. The construction minimizesthe tendency of severe jars or tilts through large angles to change theposition of the movable contacts I2 relative to the stationary contactsI0.

Our invention also contemplates improvements in moving contactassemblages for circuit controlling devices. In our preferredconstruction, the moving contact member I2 is supported from the shaftbar 26 through the medium of a. bracket 56. This bracket is of acomparatively heavy and rugged construction and is provided with a pairof extensions 58 and 60 which project at substantially right angles inthe manner shown. The end of the body portion of the moving contactmember'IZ has an opening 62 into which the projection 60 may be fittedwhile the front portion of the contact member body is provided with aslot 64 adapted to accommodate the projection 58. To impart a smallsliding movement to the engaging surfaces of contacts I2 and I0,thepoint 60 of movable-member pivot is slightly displaced (see Fig. 2)from the bearing pin 28 about which the movable assemblage rotates.

In assembling the combination (see Fig. 5) the projection 58 is firstengaged with slot 64 and opening 62 is then aligned with projection 60.Next the compression spring 33 is placed in position. It serves to holdparts I2 and 56 in operative relation without the aid of screws, boltsor clips. The arrangement thus allows the parts readily to be assembledor replaced.

'I'he contact member I2 is preferably of copper and the bracket 56 ofsteel or other wear-resisting material. As wear takes place during use,the comparatively long length of these parts prevents any substantialchange in contact alignment. This allows the contacts to be used muchlonger than otherwise. Also practically no wear is sustained by thehard-metal bracket 56. Replacement of the copper contact members thusrestores the assemblage to its original condition.

In order to increase the speed of contact separation and to prevent wearalong the sides of slot 64 of the copper member I2, this slot is madewider at the top than at the bottom. Projection 58 occupies the lowerand narrower portion of the slot when the contactor is in the openposition shown in Figs. l and 3. As the magnet rotates shaft bar 26 intothe contact-engaged position, the face of member I2 iirst strikes thatof 'cooperating contact member I0. 'I'his centralizes slot (see Figs. 4and 5), the widening dimension causes a complete separation whicheliminates wear of the slot side.

` This'elimination of drag also allows the moving shaft-bar brackets 56to accelerate at maximum speed during the opening operation. The suddenimpact of hammer blow finally imparted to contacts I2 separates themfrom stationary members II) in the minimum of time. Such quickseparation prolongs contact life and increases rupturing capacity.

The moving contact parts are further so designed that. during theopening operation the projection 56 strikes the member I2 substantiallyat its center of percussion about the stationary end of the contact.This further insures maximum speed of separation and eliminateschattering by imparting to the contact I2 at the moment of separationfrom the contact I0 a speed in excess of the speedof the bracket 56.

The presence of the slot 64 in the particular position shown alsoaccomplishes an electrical function. Iny order that the arc quenchingapparatus 23 may function most effectively, it is desirable that theblow-out coil 25 urge the arc into the box interior in a substantiallycentral position. However, the contact members I0 and I2 may, inseparating, initiate the arc at practically any point along their lineof contact or width.

When the portion of member I2 which carries the slot 64 is solid as inprior art constructions, an initiation of the arc at one side of thecontact center results in a direction into the arc box toward that side.Instead4 0i' tending to bring the arc back into the desired center, thetendency is to cause it to depart further from the center. 'I'his is dueto magnetic interactions resulting from unequal current 'distributionthrough the moving contact body.

By placing the slot 64 in the position shown, however, a very beneiicialcompensating action results. An arc started at the side of the contactstends to be restored toward the center of the arc box interior. Hereagain the explanation is magnetic interaction.

The presence of the slot requires ,that the total current divide throughthe -two parallel paths around thev slot. The distribution between these2,200,070 3 two paths varies with the point at which the arc relationand to determine the pressure of contact is drawn. If this point is atthe center, the distribution is uniform. If at one side, a major portionof the current flows through the path at that side since that path isshorter in effective length than is the other.

' The magnetic interactions resulting under these conditions stronglytend to restore the arc, in its movement away from the contacts, to apath l approaching the center of the arc box 23. In practice, thiseffect is found greatly to increase the eillciency of arc extinction.

Although we have shown and described certain specific embodiments of ourinvention, we arc u fully aware that many modifications thereof arepOssble. restricted except' insofar as is necessitated in the prior artand by the scope 'of the appended ,l claims.

We claim as our invention: i

1. In a device comprising stationary and movable contact members, thecombination of a rotatively movable supporting and actuating bracket forthe movable member having two extensions 35 spaced radially with respectto the axis of rotation and projecting in planes at about right anglesto each other, a body portion for the movable member having openingsadapted to accommodate said extensions, and a compression spring 30'adiacent one end ofthe body portion adapted to hold said parts in.operative relation and to determine the pressure of contact engagement.

2. In a device comprising stationary and movable contact members, thecombinationof a rotatively movable supporting and actuating bracket forthe movable member having two extensions spaced radially with respect tothe axis oi rotative movement and projecting in planes at about rightangles to each other. saidmovable 40Ymember having a slot near itscontact-making end adapted to accommodate one of said extensions and anopening in the opposite end adapted to accommodate the other. and acompression spring adjacent one end of the body portion 45 adapted tohold said parts in operative relation and to absorb all slack in thelost-motion connection of which said slot forms a part. L

3. In a device comprisingr stationary and movable contact members and anactuating bracket 50 for the. movable member. the combination of aprojection from said bracket..a movable-member body portion having aslot adapted to accommodate said projection. said slot being narrower atoneend than at the other. and resilient means 55 adapted to bias saidmit-.enen toward the nsfrow end of said slot and to allow it to move to-'ward the wide end when the movable member has been brought intoengagement with the stationary contactmember.

60 4. In a circuit-controlling device. the combination of a movablecontact member provided with a slot narrower at one end than at theother. an actuatingr member carrying a projection which engages saidslot. and resilient means 65 interconnectingr said members adapted tobias said projection toward the narrow end of said slot.

5. In a device comprising stationary and movable contact members. thecombination of a sup- 70 porting and actuating bracket for the movablemember having two spaced extensions projecting at about right angles. abody portion for the movable member having openings adapted toaccommodate said extensions, and a compression 75 spring adapted to holdsaid parts in operative Our invention therefore, is not to belengagement, the bracket and movable contact member being so proportionedand arranged that,

after a slight motion of the bracket in a direction to separate thecontact members, it strikes 5 the movable .contact member substantiallyat its center of percussion to effect separation of the contacts.

6. In a device comprising stationary and movable contact members, thecombination of a sup- 1o porting and actuating bracket for the movablemember for hingedly supporting one end of the movable member andprovided with an extension,

a body portion for the movable member having an opening adjacent thecontacting end for slidably accommodating said extension, and acompression spring adapted to hold said parts in operative relation andto determine the pressure of contact engagement, the opening in saidmovable member permitting a predetermined movel0 ment of the bracket ina contact separating direction prior to separation thereof from thestationary contact members, the position of said opening in said movablemember being substantially at the center of percussion of the o movablecontact member about its hinged end to effect a rapid separation of thecontact members upon receiving an impact from the bracket.

'7. In a device comprising stationary and movable contact members, thecombination of a supporting and actuating bracket for hingedlysupporting the movable member and adapted to engage said movable memberat a point corresponding substantially to its center of percussion aboutits hinged point, and a compression spring adapted to hold said parts inoperative relation and to determine the pressure of contact engagement,said movable member being biased against the pressure of said springupon engagement with said stationary member to separate the part of themovable contact member corresponding to its center of percussion fromen- 'gagement with the cooperating portion of the bracket to preset themovable contact member for rapid separation from the stationary contactmember upon an impact from the bracket at its center of percussion.

8. In a circuit controlling device comprising stationary and movablecontact members, in combination, a rotatively movable supporting member,a bracket mounted thereon for carrying the movable contact member andhaving two spaced extensions adjacent the outer and inner eids thereof,the inner projection extending substantially in the direction of motionof movement about the axis of rotative movement of the device and theouter projection extending outwardly therefrom, a body portion for themovable member having openings adapted to receive said extensions, and acompression spring adja- 50 ,cent the outer end of the body member forholding said bracket and body member in operative relation and fordetermining the pressure of contact engagement.-

i 9. In a circuit controlling device comprising stationary and movablecontact members, in combination, a rotatively movable supporting member,a bracket mounted thereon for carrying the movable contact member andhaving two spaced extensions adjacent the outer and inner ends thereof,the inner projection extending substantially in the direction of motionof movement about the axis of rotative movement of the device and theouter projection extending outwardly therefrom, a body portion for themovable member having an opening at its inner end adapt` ed to receivethe inner extension from the bracket to form a tulcrum of movement withrespect to the bracket and an upturned outer end having an openingadapted to receive the other extenvsion from the bracket, and acompression spring adjacent the outer end of the body member for holdingsaid bracket and body member in operative relation and for determiningthe pressure of contact engagement.

10. In a circuit controlling device comprising stationary and movablecontact members, in combination, a supporting and actuating bracket forthe movable member for hingedly supporting one into engagement with thestationary contact 10 member.

GEORGE C. ARMSTRONG. DELBERT ELLIS.

